The present invention relates to valves, and in particular, but not exclusively, to valves for controlling the discharge of liquids and gases.
When it is desired to discharge a fluid from a storage tank, the flow of fluid is regulated by means of a valve connected to an outlet of the tank. Known valves comprise a valve closure member which is engageable with, and displaceable away from a valve seat to control the fluid flow.
Conventionally, the valve closure members of such valves are biassed into engagement with the valve seat by a spring, and are displaceable away from the valve seat against the force of the spring by movement of an actuating handle. In some valves, the handle is used to actuate a cranking mechanism located on the discharge side of the valve and in which the displacement of the handle causes a finger member of the cranking mechanism located in a recess of the valve closure member to lift the valve closure member off the valve seat, and thereby allow the flow of fluid through the valve.
The problem with the known discharge valves is that the springs and/or actuating mechanisms are located in the flowpath of the fluid into or out of the valve. This can cause problems where chemically aggressive fluids are being discharged, which might necessitate manufacture of components from more expensive, chemically inert materials. It can also cause problems where pasty or sludgy products are being discharged, since the products might clog up the actuating mechanism or spring, thereby making it difficult or impossible to open or close the valve. Also, some actuating mechanisms require the valve to be located relatively high up in a frame in which a container is mounted, thereby reducing the size (and capacity) of the container which can be mounted in the frame, since the valve must be positioned at the lowest point of the container.
It is an object of the present invention to provide a valve which aims to overcome the above disadvantages.